A short specification of the MMC-specification may be downloaded from the Internet site “http://www.mmca.org/compliance/buy_spec/MMCA_System_SummaryV41.pdf”.
Boot definitions for existing embedded mass memory components having a different electrical interface are already known. These known components are e.g. NAND, OneNAND and MDOC mass memories. Common to all of these is that they are using some signal state (e.g. separate pin reserved for booting) during certain stage of power up to indicate to the memory component that it should fetch the first sector (typically 512 B) of data to the IO buffers. The technical data sheet of M-systems DiskOnChip (DOC) being cited as state of the art may be retrieved from the Internet at the address http://www.m-systems.com/NR/rdonlyres/85A96312-0130-47AD-A22C-CB533E28EE7A/0/DOC_G3—512Mb—1Gb_Rev20.pdf.
There are other known boot definitions for the other existing embedded mass memory components which has different electrical interface. These kinds of components are e.g. NAND (see: http://www.samsung.com/Products/Semiconductor/NANDFlash/index.htm), OneNAND (see: http://www.samsung.com/Products/Semiconductor/OneNAND/index.htm) and MDOC (see: http://www.m-systems.com/site/en-US/Products/DiskOnChip/DiskOnChip/) mass memories. Common to all of these is that they are using some signal state (e.g. separate pin reserved for booting) during certain stage of power up to indicate to the memory component that it should fetch the first sector (typically 512 B) of data to the IO buffers.
Present MMC- and SD-memory cards can provide capabilities of performing e.g. hot-swap operations, but it is also desirable to extend the capabilities of these memory cards to be able to provide a broader functionality.
To improve the usability of memory cards it would be desirable to enable a user to use memory cards as bootable media. This feature would enable a broader use of e.g. MMC (Multi-Media Card) and SD (Secure Digital) cards not only in self booting devices such as mobile cellular phones or cameras but also as a bootable storage medium for e.g. laptop and palmtop computers.
Presently, in the field of MMC-cards and SD-cards, the only way to access the first (sector) data during boot up of a host device is to follow the whole procedure of initializing the card, reading/writing the registers and performing a normal read access to known address.
The issue with existing MMC- and SD memory card interface protocols is that there is no efficient booting mechanism defined. The only way to access the first (sector) data during boot up of a host device is to follow the whole procedure of initializing the card, reading/writing the registers and performing a normal read access to known address. That means it is actually impossible to perform a boot procedure with a device not being configured to perform automatically a normal read access to a boot address (as e.g. the address of the boot data to be read is not known).
It is also desirable to achieve a broader usability without a necessity to change the electrical interface or the form factor, i.e. without using the signal state of an additional separate pin reserved for booting during certain stage of power up to indicate to the memory component that it should fetch a certain sector of data to the I/O buffers.
Therefore, a problem addressed by the invention involves extending the capabilities of existing MMC- and SD-cards without changing to many properties of the memory cards and to also be able to guarantee full down-compatibility.